The present invention relates to a dialing confirmation tone (DCT) output apparatus and, more particularly, to a DCT output apparatus to be connected to a receiver of a telephone and to an earphone, or a headset.
When one of its push-button keys is pressed, a push-button dial telephone set generates a DCT, or signaling tone, to inform the user that a dual tone multi-frequency (DTMF) signal corresponding to the pressed key is generated and transmitted to an exchange office. Usually, such a DCT is generated when the user dials the number of the called party. But, even after a voice channel is established, i.e., during conversation, a DCT is generated if the user dials the number representative of a control signal which remotely controls home appliances, inquires an automatic answering telephone set, gains access to computers, and so forth. If a DCT is generated during conversation, it may be added to a received voice signal.
In a conventional DCT output apparatus, a transducer which is dedicated to producing a dialing confirmation tone is installed in an earpiece of a telephone. This makes the earpiece bulky and reduces the clarity of the tone. To avoid these problems, a receiver of a telephone which outputs a received voice signal could be used for emitting the confirmation tone. Using the receiver, however, makes the user uncomfortable when the confirmation tone is produced during conversation, because the user has to keep the receiver close to his ear to listen to the conversation. Similarly, if an earphone is employed to hear the conversation instead of the receiver, a loud confirmation tone reaches the user's ear, making him uncomfortable.